World's Smallest Hydrophone for Scuba Divers

Build
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As far as I can tell, this is the smallest hydrophone for scuba divers in the world that can sample rate up to 384 kHz, meaning it can detect cetaceans (whales, dolphins, porpoises) sound clicks. Might also be useful for listening to other underwater critters. The enclosure is BR smallest (2 inches) diameter. Custom electronic board and preamp inside.
Next are the experiments in various conditions.

20240927_151145
20240927_1511451920×3413 275 KB

4 Likes
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Hi @bajaMike,

This looks really cool - thanks for sharing! :smiley:

A few questions:

  1. Does it have some kind of live output/indicator capability (e.g. to show there are whales nearby), or is it specifically for recording during the dive, with all processing and analysis coming afterwards?
  2. How long can it run for?
  3. How much can it record?
  4. Is it possible to retrieve the data and/or recharge the battery without opening the enclosure?
3

Hi Eliot,

Thanks for your kind words. Answers:

  1. No indicators. Passive recording only.
  2. Hours usually, depending on the selection of sample rate.
  3. SD card limits.
  4. Need to open up to get at the data and recharge.
    With the above limits, it can be very useful to set the device in a secure spot and return later for the device. Other PAM recorders require an experienced crew to secure the device to a mooring line.